Photoflash lamp with printed circuit lead-in conductors



N. F. BAIRD Nov. 30, 1965 PHOTOFLASH LAMP WITH PRINTED CIRCUIT LEAD-IN CONDUCTORS Filed Jan. 51, 1965 Fl G. 6.

FIG. 5.

FIG. 8.

INVENTOR NORMAN F. BAI RD \IIIDIIVWVIMVIII 1 I i FIG. I3.

FIG. 9. XI

ATTOR N EY.

United States Patent 3,220,225 PHOTOFLASH LAMP WITH PTED CIRCUIT LEAD-IN CONDUCTORS Norman F. Baird, Bloomfield, N.J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 31, 1963, Ser. No. 255,258 9 Claims. (Cl. 6731) The present invention relates to photoflash lamp constructions.

There is a continual demand to simplify the construction and reduce the cost of photoflash lamps since such devices are expendable in use. In order to reduce the cost of photoflash lamps, it has been proposed to construct a photoflash lamp envelope of radiation-transmitting plastic material and to enclose a quantity of flashproducing material within the envelope which is then sealed to contain the forces produced when the flashproducing material is ignited to generate the desired radiation. Reference may be made to the copending patent application, Serial No. 197,639 of Norman F. Baird, filed May 25, 1962 and assigned to the same assignee as the subject application, for a more detailed disclosure of one type of plastic envelope photoflash lamp.

The present invention relates, in its more specific aspects, to an improvement in the photoflash lamp dis closed and claimed in the aforesaid Baird application Serial No. 197,639.

Another important cost in the manufacture of photoflash lamps is related to the manner of inserting, assembling and sealing the electrical conductors that extend from external electric contact or terminal surfaces on the lamp envelope to the electrical ignition means within the lamp envelope.

It is a principal object of the present invention to provide an improved and simplified photoflash lamp that may be very inexpensively constructed.

Another object of the invention is to provide an improved construction of photoflash lamp having a simplified arrangement of electrical ignition means and associated electrical conductors within the lamp for connection to external electrical terminals on the lamp.

Yet another object of the invention is to provide an improved photoflash lamp construction of the electrically ignited type which simplifies the manner of sealing the lamp where the electric conductors for the ignition means within the lamp are passed to external electric terminal elements.

A feature of the invention is the provision of homogeneous electrical conducting means extending on internal surfaces of the lamp envelope from the electric filament or other ignition means within the lamp to external electric contact or terminal surfaces on the exterior of the lamp. Such homogeneous electrical conducting means suitably comprises a deposit of electrically conductive coating material more commonly known as a printed circuit which is applied by any known procedure such as stamping or roll coating on the interior surface of the lamp envelope before it is sealed. Thereafter the lamp envelope with the printed circuit conductors thereon is sealed with the printed circuit conductors extending between the sealed surfaces to the external electric terminal or contact means on the lamp. The use of printed circuit conductors as briefly described above is particularly suitable in the manufacture of plastic envelope photoflash lamps although it is not limited thereto. An important advantage of the invention in the use of printed circuit conductors from external terminal elements to the internal electric ignition means is that the primer means may be deposited directly on the interior surface of the lamp envelope at any desired position Within the lamp.

Further objects, features and the attendant advantages of the invention will be apparent with reference to the following specification and drawing in which:

FIGURE 1 is a perspective view of one form of photoflash lamp constructed in accordance with the invention;

FIG. 2 is a perspective view of an end plug for use with the lamp of the invention shown by FIG. 1;

FIG. 3 is a longitudinal cross-section on the line III III of FIG. 1;

FIG. 4 is a cross-section in the direction of the arrows on the line IV1V of FIG. 3;

FIG. 5 is a perspective view of another form of photoflash lamp embodying the invention;

FIG. 6 is a sectional view of an end plug as used with the form of the invention shown by FIG. 5;

FIG. 7 is an end view of the plug shown by FIG. 6;

FIG. 8 is a top plan view of a yet another modified form of the invention;

FIG. 9 is a side elevational view with fragmentary section of the lamp construction of FIG. 8;

FIG. 10 is a fragmentary cross-section in the direction of the arrows on the line XX of FIG. 8; a

FIG. 11 is a cross-section in the direction of the arrow on the line XI-XI of FIG. 9;

FIG. 12 is an elevational view partly in section of yet another form of photoflash lamp embodying the invention;

FIG. 13 is a section taken on the line XIH-XIII of FIG. 12; and

FIG. 14 is a top view of the modified form of photoflash lamp shown by FIG. 12 of the drawing.

Referring now to FIGS. 1-4 of the drawing, a first embodiment of the invention will be described. As shown, the lamp envelope comprises a tube 10 of radiation-transmitting plastic material. As disclosed in more detail in the aforementioned patent application Serial No. 197,639, the tube material may be cellulose acetate propionate with a wall thickness of about 40 mils, and for example, the tube 10 may contain a volume of about 7.3 cc. of air at atmospheric pressure which is sealed by the end plugs 11 and 12 formed of any suitable plastic material that is compatible with the material of the enevelope tube 10. Each of the end plugs 11 and 12 is provided with a coating of electrically conductive material 13 on an external surface thereof to comprise external electrical contact terminals. In accordance with the invention, electrical conductors 15 and 16 (of'homogeneous material) extend along an interior surface of the envelope 10 from the respective terminal plugs 11 and 12 to opposite ends of the filament wire 17 which may be tungsten or the like. Although the filament 17 has been described as a tungsten wire, it should be understood that other types of filamentary materials may be employed. The filament 17 is electrically connected to the respective ends of the conductive elements 15, 16 by any suitable means and may be held in position to be spaced from the surface of the lamp envelope by the deposit of primer material 2.0 to be later described.

In the form of the invention being described in connection with FIGS. 1-4 of the drawings, a quantity of flashproducing material 21 which may be present in an amount of milligrams is deposited on the envelope wall at a point spaced from the primer 20 and filament 17. By way of example only, the flash-producing material may be formed of a mixture of finely divided zirconium and finely divided barium nitrate with a suitable binder, where the molar ratio of zirconium to barium nitrate is 3:1. For a more detailed disclosure of flash-producing materials, reference may again be made to the aforementioned patent application, Serial No. 197,639.

The electrical conductors and 16 are preferably comprised of deposits of electrically conductive material of any of the known compositions used for printed circuits. As an example of a suitable composition for applying the printed circuit, silver oxide is suspended in amyl acetate vehicle which contains a small amount of nitrocellulose binder. There is also included a reducing agent such as hydrazine sulfate whichserves to convert the silver oxide to silver when heated to relatively low temperatures. Such printed circuit coating compositions are Well known in the art and other known compositions can be substituted for the example as given hereinbefore.

Prior to the insertion and sealing of the end plugs 11 and 12, and before the deposit of the primer and filament 17, the electric conductors 15 and 16 may be formed on the interior surface of the envelope 10 by means of printing, stamping, or roller coating or any other suitable printed circuit technique that is known in the art. Thereafter, filament 17 and the primer 20 may be deposited as shown by FIGS. 1, 3 and 4 of the drawing. It will be noted that the respective printed circuit conductor elements 15 and 16 extend between the sealing surfaces of the tube 10 and the sealing surfaces of the end plugs 11 and 12 to the respective electrical contact or terminal surfaces 13 and 14 on the end plugs. Also, if desired, conductive paths, such as the path 19, may be formed on the end plug as shown by FIG. 2. of the drawing. Such paths as the path 19 will be aligned with a respective one of the conductive paths 15, 16 when the lamp is assembled and the end plugs emplaced.

Referring now to FIGS. 5-7 of the drawing, a modified form of the invention will be described. The lamp envelope is formed by a tube of radiation-transmitting material integrally closed at one end in the form of a test tube or the like. The open end of the tube 30 is closed by a plug 31 having spaced and electrically insulated external electrical contact surfaces 32 and 33 thereon. Again the envelope 30 may be formed of cellulose acetate propionate while the end plug 31 may be of any suitable plastic electrically insulating material. For purposes of this description, the tube 30 may enclose a volume of about 7.3 cc. of air at atmospheric pressure. The electrical terminal surfaces 32 and 33 may be formed on the end plug by any suitable printed circuit technique and they are also formed at 34 and 35 (FIG. 7) to extend along an end surface of the plug 31 which in the assembled relation is effectively an interior surface of the photoflash lamp. The ends of the electrical conductors 34 and 35 are joined by a filamentary portion 36 such as a tungsten wire which is surrounded by a quantity of primer material 37. The primer 37 which may be present in any suitable amount, such as for example about 6 milligrams, is preferably formed of a mixture of finely divided zirconium and potassium perchlorate in such relative proportions that all of the oxygen in the perchlorate will react with all of the zirconium during firing. A quantity of about 90 milligrams of flash-producing material 38 is deposited on the opposite end of the flash lamp tube 30 to be ignited by the firing of the primer material 37 when an electric current is passed through the filament 36.

In the form of the invention shown by FIGS. 8-11 of the drawing, the photoflash lamp envelope may be comprised of two halves 40 and 41 of a plastic envelope formed of cellulose acetate propionate or the like. The envelope half setcions 40 and 41 are sealed together along their flange portions 42 and 43 in any known manner such as by heat sealing or adhesive sealing, or crimping. A quantity of flash material 45 may be deposited at one end of the lower half envelope 41 while printed circuit conductors 46 and 47 may be formed along the interior surface of the upper envelope half 40 before assembly. A quantity of priming material 48 and a tungsten firing filament 49 is provided between the interior ends of the printed circuit conductors 46 and 47 as shown. When the lamp envelope halves 40 and 41 are sealed together, the printed circuit conductors 46 and 47 extend between the sealed flange surfaces 42, 43 to external contact terminal elements 50 and 51 respectively. Again, it should be understood that the electrical conductors 46 and 47 may be formed on and along the interior surface of the photoflash envelope half section 40 by any of the well known printed circuit techniques. Since the electrical conductors 46 and 47 are printed circuit coatings, there are no difliculties encountered in sealing the two envelope halves 40 and 41 together at their flange surfaces 42 and 43.

Yet another embodiment of the invention is shown by FIGS. 12 through 14 of the drawing where the lamp envelope of plastic material is formed into a bulb shape 60 having a neck portion 61 which is sealed at 62 by a hot press seal. Printed circuit conductors 63 and 64 extend along an interior surface of the lamp envelope 60 from the ignition filament 65 and primer material 66 to the external contact surfaces 67 and 68. Of course, the printed circuit conductors 63, 64 are spaced from each other where they pass through the seal 62. A deposit 69 of flash-producing material is affixed to a side wall of the bulbous envelope 60 at a point spaced from the primer 66.

Various modifications will occur to those skilled in the art. For example, although a tungsten filament wire has been specifically mentioned, it should be understood that other electrically resistive materials may be used. An important aspect of the invention is that the filament is spaced from the lamp envelope wall by a quantity of primer material so that the filament can be energized to become hot enough to decompose the oxidant of the primer material to form an exothermic reaction and cause incandescent particles to fly at high speeds and strike the light producing material spaced therefrom within the lamp.

I claim as my invention:

1. A photoflash lamp comprising, a radiation-transmitting sealed enclosure, external electrical contact means on said enclosure, a quantity of flash-producing material within said enclosure adapted to be ignited to generate radiation, electrical ignition means within said enclosure to ignite said flash-producing material, and an adherent coating of electrically-conductive material on the interior surface of said enclosure defining a printed circuit which connects said ignition means to said contact means.

2. .A photoflash lamp comprising, a radiation-transmitting enclosure having a sealed end portion, electrical contact means on said enclosure proximate said sealed end portion, a quantity of flash-producing material within said enclosure adapted to be ignited to generate radiation, electrical ignition means within said enclosure adapted to ignite said flash-producing material, and an adherent coating of electrically-conductive material on the interior surface of said enclosure extending through the sealed end portion thereof and defining a printed circuit which connects said ignition means to said contact means.

3. A photoflash lamp comprising, a radiation-transmitting envelope, a pair of electric terminal surfaces on said envelope, a quantity of flash-producing material within said envelope adapted to be ignited to generate radiation, a quantity of primer material on an inside wall of said envelope, a filamentary element overlying said quantity of primer material and adapted to be heated by the passage of electric current therethrough to thereby ignite said primer material and flash-producing material, and a deposit of adherent electrically-conductive material on said envelope defining a pair of spaced printed circuit conductor elements that are electrically connected to the ends of said filamentary element and extend along an interior surface portion of said envelope to respective ones of said pair of electric terminal surfaces.

4. A photoflash lamp comprising a radiation-transmitting tube, at least one stopper inserted in an end of said tube to thereby seal the tube in the assembled relation, a radiation-generating material sealed within said tube and adaptedto be ignited to generate radiation, electric ignition means sealed within said tube and adapted to be energized to ignite said radiation-generating material, electric terminal means on an external surface of said stopper, and printed circuit electric conductor means comprising a deposit of adherent electrically-conductive material on said tube that extends along the interior surface of said tube from said electric ignition means and between opposing surfaces of said stopper and tube to said electric terminal means.

5. A photofiash lamp comprising a radiation-transmitting tube open at one end, a stopper inserted in the open end of said tube to thereby seal the tube in the assembled relation, a radiation-generating material sealed within said tube and adapted to be ignited to generate radiation, electric ignition means sealed within said tube and adapted to be energized to ignite said radiation generating material, electric terminal means on an external surface of the assembled tube and stopper, and a deposit of adherent electrically-conductive material on said tube defining a pair of printed circuit electric conductor elements that extend in spaced relation to each other along an interior surface portion of said tube from said electric ignition means and between opposing surfaces of said stopper and tube and connect said ignition means to said electric terminal means,

6. A photofiash lamp comprising a radiation-transmitting tube open at each end, a stopper inserted in each end of said tube to thereby seal the tube in the assembled relation, a radiation-generating material sealed within said tube and adapted to be ignited to generate radiation, electric ignition means sealed within said tube and adapted to be reacted to ignite said radiation generating material, an electric terminal means on an external surface adjacent each of the respective ends of the assembled tube and stoppers, and a deposit of adherent electrically-conductive material on said tube defining printed circuit electric conductor elements that extend in opposite directions along an interior surface portion of said tube from said electric ignition means and between the opposing surfaces of said stoppers and tube to respective ones of said electric terminal means.

7. A photoflash lamp comprising, a radiation-transmitting envelope having a seal at one end, a pair of exposed terminals on said envelope, a quantity of flashproducing material located on the inner surface of said envelope, a quantity of primer material deposited on the inner surface of said envelope and adapted to be reacted to ignite said flash-producing material, a filament in contact with said primer material and arranged so that a portion of the filament is held in spaced apart relation with the envelope wall by said primer material, and a pair of spaced printed circuit conductor elements comprising an adherent coating of electrically conductive material extending from the ends of said filament along the inner surface of said envelope and through said seal to the respective terminals.

8. A photoflash lamp as set forth in claim 7 wherein; said envelope comprises a plastic open-ended tube having a plastic plug inserted into and closing each end, said terminals are carried by said plugs, and the adherent coating comprising said printed circuit conductor elements extends between the abutting surfaces of said plugs and tube.

9. A photoflash lamp as set forth in claim 7 wherein; said envelope comprises a plastic bulb having a neck portion that is closed by a press seal, said terminals are carried by and overlie preselected portions of the press seal, and the adherent coating comprising said printed circuit conductor elements extends through the press seal to said terminals.

References Cited by the Examiner UNITED STATES PATENTS 2,197,733 4/ 1940 Schwarze 5 67-31 2,205,081 6/1940 Burrows et a1 67-31 2,289,876 7/1942 De Margitte 67-31 2,325,667 8/ 1943 De Boer 67-31 2,333,725 11/ 1943 Kreidler 67-3 1 2,361,495 10/ 1944 Pipkin 67-31 2,375,742 5/ 1945 Kalil et al 67-31 2,844,018 7/ 1958 Schwartz et a1. 7-58 2,955,447 10/1960 Fink et a1. 67-31 2,981,088 4/1961 Kaprelian 67-31 FOREIGN PATENTS 120,915 2/ 1946 Australia. 551,004 5/ 1932 Germany. 551,670 6/1932 Germany.

EDWARD J. MICHAEL, Primary Examiner. 

1. A PHOTOFLASH LAMP COMPRISING, A RADIATION-TRANSMITTING SEALED ENCLOSURE, EXTERNAL ELECTRICAL CONTACT MEANS ON SAID ENCLOSURE, A QUANTITY OF FLASH-PRODUCING MATERIAL WITHIN SAID ENCLOSURE ADAPTED TO BE IGNITED TO GENERATE RADIATION, ELECTRICAL IGNITION MEANS WITHIN SAID ENCLOSURE TO IGNITE SAID FLASH-PRODUCING MATERIAL, AND AN ADHERENT COATING OF ELECTRICALLY-CONDUCTIVE MATERIAL ON THE INTERIOR SURFACE OF SAID ENCLOSURE DEFINING A PRINTED CIRCUIT WHICH CONNECTS SAID IGNITION MEANS TO SAID CONTACT MEANS. 